The invention relates to a paper feed mechanism for printing and typing equipment.
In paper feed mechanisms of the type referred to, it is generally known that the paper transport shaft of such mechanisms can be made releasable in order to facilitate insertion of paper into the printing equipment or in order to allow adjustments of the paper already in the printing equipment. Thus, in German patent DE-PS No. 30 14 340 a mechanism for engaging and disengaging a paper transport shaft from a platen of a typewriter is described where by means of locking arrangement the paper transport shaft supported on one side can be pivoted away from the platen for the purpose of transporting edge-perforated paper. When using paper not perforated along the edge, the transport shaft with a transport roller arranged thereon are used for holding the paper against the platen of the printing equipment.
Besides their complicated construction, these known devices have the disadvantage that while they allow engagement and disengagement of the paper transport shaft, they do not allow adjustment of contact pressure between the paper pressure roller of the paper transport shaft and the platen as required for accommodating papers of various types.
Yet, in a typical setting, printing mechanisms are used for the generation of permanent records on paper of various types and sizes. For example, endless paper, endless paper with carbon copies, or single sheets of paper need to be used with the traditional printing equipment mentioned above. It is therefore important to provide an adjustable contact pressure between the paper roller and the platen in order to adapt to different printing mediums and in order to ensure a safe and smooth operation of the printing equipment.